1. Field of the Invention
This invention relates to an electrical connector assembly with means for reducing the mating forces and reducing contact wear.
2. Description of the Prior Art
In U.S. Pat. No. 2,992,401, a connection assembly is disclosed comprising a first connector having a plurality of bus bars for mating with receptacle terminals mounted in a complementary connector. The receptacle terminals are received in channels of the first connector aligned with the bus bars. Protrusions are provided in the cavities proximate mating ends of the bus bars such that cantilever beam contact arms of the receptacle terminals are pried apart prior to insertion of the bus bar between cantilever beam contact arms of receptacle terminal.
The protrusions may be formed of a smooth profile from the insulating material of the housing such that force required to pry apart the receptacle terminal contact arms is lower than if the contact arms were pried apart by the bus bar. It is easier to adapt the profile of the projection to an ideal contact separating profile in view of reducing mating forces, than adapting the tip of the bus bar. Housings are typically injection moulded where complex profiles can be easily formed, compared to terminals which are made typically of stamped and formed metal. Furthermore, the coefficient of friction between housings (typically made of plastic) and the metal contact arms of the receptacle contact is lower than between mating contacts. Furthermore, separating the receptacle contact arms with the protrusion reduces contact wear.
The above described connector assembly however is longer in view of the extra length required for the cavities and protrusion. It is a desire not only to render connectors more compact, but to reduce costs while increasing reliability.
For example certain applications contact surfaces are provided with a thin layer of gold in order to prevent corrosion forming on the contact surfaces which leads to increased contact resistance. In order to save gold and decrease plating times, it is desirable to provide a very thin gold layer. In conventional connectors however after a few plugging and unplugging cycles the gold layer is often rubbed away. Although utilization of a concept according to U.S. Pat. No. 2,992,401 would enable an increase in the number of mating cycles, the contact surfaces of the terminals nevertheless rub against the insulator, which may eventually lead to the gold wearing through. A further problem is the risk of plastic from the protrusions rubbing off onto the contact points thereby increasing contact resistance or even insulating the contacts.
It is also increasingly important to provide robust connectors, and in particular robust terminals with low risk of damage such that reliable interconnection is provided, particularly where electrical interconnections relate to safety devices.
A further important aspect in order to provide reliable interconnection is to ensure that complete mating and electrical connection occurs when coupling connectors together. In particular, an intermediate position where mating contacts are only partially coupled is undesirable.